Fluid catalytic cracking (FCC) is a hydrocarbon conversion process accomplished by contacting hydrocarbons in a fluidized reaction zone with a catalyst composed of finely divided particulate material. The reaction in catalytic cracking, as opposed to hydrocracking, is carried out in the absence of substantial added hydrogen or the consumption of hydrogen. As the cracking reaction proceeds, substantial amounts of highly carbonaceous material, referred to as coke, are deposited on the catalyst to provide coked or carbonized catalyst. This carbonized catalyst is often referred to as spent catalyst. In conventional processing, vaporous products are separated from the carbonized catalyst in a reactor vessel. Carbonized catalyst may be subjected to stripping in the presence of a gas such as steam to strip entrained hydrocarbonaceous gases from the carbonized catalyst.
The carbonized catalyst is regenerated before catalytically cracking more hydrocarbons in the presence of the catalyst. Regeneration occurs by oxidation of the carbonaceous deposits to carbon oxides and water. To regenerate the carbonized catalyst, the carbonized catalyst is introduced into a fluidized bed at the base of the regenerator, and oxygen-containing combustion air is passed upwardly through the bed. After regeneration, the regenerated catalyst is returned to the riser.
Entrained gases are generally present along with the regenerated catalyst after regeneration. The entrained gases may include inert gases such as nitrogen, or corrosive gases such as carbon monoxide, carbon dioxide, and oxygen. Conventional processing feeds the regenerated catalyst with the entrained gases to the reactor vessel. As a result, the reactor vessel may be required to process increased amounts of material and may be negatively impacted by corrosive entrained gases.
Accordingly, it is desirable to provide FCC units, separation apparatuses, and methods for separating regenerated catalyst from entrained gases. In addition, it is desirable to provide apparatuses and methods for separating entrained gases from regenerated catalyst within a regeneration vessel before the regenerated catalyst exits the regeneration vessel. Furthermore, other desirable features and characteristics will become apparent from the subsequent detailed description and the appended claims, taken in conjunction with the accompanying drawings and this background.